Machining Characteristics and Optimization of Machining Parameters of SKH 57 High-Speed Steel Using Electrical-Discharge Machining Based on Taguchi Method

The effects of the machining parameters in electrical-discharge machining (EDM) on the machining characteristics of SKH 57 high-speed steel were investigated. A well-designed experimental scheme was used to reduce the total number of experiments. Parts of the experiment were conducted with the L18 orthogonal array based on the Taguchi method. Moreover, the signal-to-noise ratios associated with the observed values in the experiments were determined by ANOVA and F-test. The significant parameters that critically influenced the machining characteristics were examined, and the optimal combination levels of machining parameters for material removal rate, electrode wear rate, and surface roughness were determined.     

Study of Electrical Discharge Machining Performance in Water-Based Working Fluid

In this study, the role of working fluid in electrical discharge machining (EDM) was investigated based on its electrical conductivity. The function of gas bubble in material removal process was studied by comparing the crater that formed in water discharge with that formed in air discharge. The mechanism of material removal for EDM in water-based working fluid was proposed by analyzing the discharge voltage. Experiments were conducted to learn the influence of discharge parameters and working fluid conductivity on the crater forming process. The detected discharge waveform demonstrated that the effect of electrolytic reaction in the discharge process could be controlled by changing the conductivity of the working fluid. This study shows that water-based working fluid has good application prospects in EDM machining.     

Investigation of the Tool Wear Rate in Tungsten Powder-Mixed Electric Discharge Machining of AA6061/10%SiCp Composite

This paper presents the experimental investigation on tool wear rate (TWR) in powder-mixed electrical discharge machining (PMEDM) of aluminum 6061 alloy reinforced with 10% silicon carbide particles (AA6061/10%SiC_p composite). Composite material is fabricated by mechanical stir casting process and further characterized by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Tungsten powder with concentration of 4 g/L is mixed in the dielectric fluid. To know the influence of powder suspension in dielectric fluid on TWR, comparative study is done on the basis of experiments performed using basic EDM and PMEDM process. Experiments have been designed as per central composite rotatable design (CCRD) using response surface methodology (RSM) approach. Four process parameters, namely, peak current, pulse-on time, pulse-off time, and gap voltage have been considered for TWR investigation. Individual and interactive influence of various parameters on TWR is explained with the help of analysis of variance and three-dimensional graphs. Using RSM approach, results have been further optimized. PMEDM approach provides 51.12% reduction in TWR for machining of AA6061/10%SiC_p composite.     

Effect of Powder Mixed Dielectric on Material Removal and Surface Modification in Microelectric Discharge Machining of Ti-6Al-4V

Microelectric discharge milling is one of the variants of microelectric discharge machining process which acquire the attention of researchers due to its unique ability to produce microchannels and three-dimensional structures in difficult-to-machine materials like titanium. In the present work, an experimental investigation has been performed in order to study the effect of SiC microparticle suspended dielectric on machining Ti-6Al-4V with tungsten carbide electrode. The effects of major electric discharge milling process parameters—voltage, capacitance, and powder concentration in dielectric—on responses—viz., material removal rate (MRR) and tool wear rate (TWR)—were studied. Experiments were designed and performed based on response surface methodology (RSM)-Box–Behnken statistical design and the significance of in put parameters were identified with the help of analysis of variance. From the results, it is recommended to use powder concentration of 5 g/L, capacitance of 0.1 µF, and voltage of 115 V for achieving high material removal and low tool wear rate. Finally, the studies were conducted to analyze the surface modification and the quality of machined surface.     

Modeling and Analysis of Machinability Evaluation in the Wire Electrical Discharge Machining (WEDM) Process of Aluminum Oxide-Based Ceramic

The wire electrical discharge machining (WEDM) allowed success in the manufacture of the hard, fragile, and materials difficult to cut, especially for electroconductive ceramic materials. In this study, the mathematical models of material removal rate (MRR) and surface roughness (SR) used for the machinability evaluation in the WEDM process of aluminum oxide-based ceramic material (Al₂O₃ + TiC) have been carried out. The experimental plan adopts the face centered central composite design (CCD). The mathematical models using the response surface methodology (RSM) are developed so as to investigate the influences of four machining parameters, including the peak current, pulse on time, duty factor, and wire speed, on the performance characteristics of MRR and SR. It has been proved that the proposed mathematical models in this study would fit and predict values of the performance characteristics, which would be close to the readings recorded in experiment with a 95% confidence level. The significant parameters that critically affect the performance characteristics are examined.     

常用高速切削刀具材料的性能分析与应用

要实现高速切削加工,刀具材料是关键,高速切削技术是随着刀具技术如刀具材料等的发展而发展起来的。本文介绍了高速切削加工中常用的聚晶金刚石、立方氮化硼、陶瓷、Ti(C,N)基金属陶瓷等材料和涂层刀具等的特性、应用范围和发展趋势,以促进高速切削技术的广泛应用。     

油田电泵井套管杂散电流腐蚀排流设计及应用

为加强对油田电泵井套管的腐蚀控制,通过室内模拟交流杂散电流腐蚀试验,考察了交流杂散电流对电泵井套管的腐蚀性.结果表明:试样腐蚀速率随着电压的增加而增大,随介质电阻率的增大而减小,电泵井套管的腐蚀存在杂散电流腐蚀及土壤电化学腐蚀的双重强腐蚀.该区域土壤具有较强的腐蚀性,虽然杂散电流并不连续,但可加剧土壤电化学腐蚀.确定采用排流保护法并设计了牺牲阳极排流方案来控制腐蚀.现场测试表明,管地电位波动范围由措施前的124.0 mV减少至27.1 mV,管地电位可负移至一850.0mV(相对饱和硫酸铜参比电极),保护率为78.1%,达到了石油行业标准规定的防腐蚀要求.